Embodiments of the inventive concepts relate to semiconductor devices and, more particularly, to semiconductor devices including semiconductor chips stacked by a wafer-level stacking method.
As high-capacity, thin, and small semiconductor devices and electronic products using the same have been increasingly in demand, various packaging techniques have been developed for such devices. In some of these packaging techniques, semiconductor chips may be vertically stacked to realize a high density chip stack structure. According to these techniques, semiconductor chips having various functions may be integrated in a smaller area than a general package having one semiconductor chip.
Some semiconductor chips may include image sensors. An image sensor may convert an optical image into an electrical signal. As computer and communication industries have developed, high-performance image sensors have been increasingly demanded in various fields such as those utilizing digital cameras, camcorders, personal communication systems (PCS), game consoles, security cameras, and medical micro cameras.
Image sensors may be categorized as either charge coupled device (CCD) image sensors or complementary metal-oxide-semiconductor (CMOS) image sensors. The driving operation of the CMOS image sensors may be simple. In addition, a single processing circuit of the CMOS image sensor may be integrated on a single chip to reduce the size of the CMOS image sensor. Furthermore, the power consumption of the CMOS image sensor may be very low. Thus, the CMOS image sensor may be used in products having a limited battery capacity.